Hashtags
A word or phrase preceded by“#.” It’s like a magnet that attracts all messages categorized by that topical word or phrase. When you tweet and want your message to be part of a larger conversation beyond your followers, add a relevant hashtag to the end of your message, and you’ll automatically reach anyone who is monitoring the same hashtag. To discover relevant hashtags, search for keywords related to the 
conversations, questions and issues you want to find. The easiest way to do this is by using the search function at the top of your Twitter homepage.
History of hashtags
Chris Messina, a former Google employee who worked in developer relations and as a designer on Google+, Tweeted the first ever hashtag. This Tweet took place all the way back in 2007, so it took quite a bit to catch on, but when it did, it did in a big way.
Importance of Hashtags
While hashtags on all social networks have the same fundamental purpose of content tagging and discovery, the use of hashtags still varies by network. In terms of use, Instagram hashtags, for example, are often more focused on description of the photo and the tools used to take it than on a broader story or theme. This is at odds with Twitter, where hashtags tend to be more focused a topic of conversation, or a group of people (a chat for example) that you would like to engage.
Using hashtags will allow you to make an impression on a wide social media audience. Make sure you’re sharing the best content, and making the right impression http://sproutsocial.com/insights/how-to-use-hashtags/
According to a research by Buddy Media (and mentioned on the Buffer app blog), one lonely hashtag can increase engagement by 100%!
Unfortunately, there are a lot of people out there who just don’t seem to understand the new trend. They misuse the organizational tool thinking that it is simply a means of attracting attention to their content. While the hashtag can serve this purpose, using it improperly isn’t going to help you at all.
I recommend http://www.jeffbullas.com/2014/05/07/how-to-use-the-power-of-hashtags-in-your-social-media-marketing/ to understand the power of hashtags in brand management.
TOP 3 HASHTAG TOOLS
https://www.hashtracking.com/ provide a free to use Hashtag Explorer tool that you can use for quick searches.
https://ritetag.com/ By adding the RiteTag extension to your web browser, you will be able to schedule your tweet from wherever you are online as well as select the best possible hashtags for your tweet.
https://tagdef.com/ Tagdef is a tool dedicated to definitions of hashtags, Whenever searching for a hashtag, apart from getting a definition, you’ll get a list of related hashtags, as well as popular hashtags. If you’re not pleased with a definition, you can even add your own in seconds!
